In concentrating maple syrup, sap collected from maple trees is fed into an evaporator having an open pan mounted on top of a wood or oil furnace. Heat supplied by the furnace causes the sap to boil and water is evaporated from the sap to leave concentrated syrup. Large scale commercialization in this industry has added various improvements to the evaporation process to improve efficiency. Most commercial evaporators now include a rear flue pan and one or more finishing pans. The larger rear flue pan has a multitude of flues in the base of the pan to increase the amount of heated surface area contacting the sap, this increases evaporation efficiency. The forward finishing pans are used to precisely concentrate the syrup to its final sugar content. A steam hood is mounted over all pans for directing steam out of the sugar house. To reduce the boiling time, a process of reverse osmosis (RO) may also be employed to concentrate the sap prior to entering the evaporator.
During the evaporation process, not only the sugar content of the sap is increased, but also that of various impurities present in sap. The primary impurity is niter (potassium nitrate), which deposits onto the evaporation pans. Residual impurities can contribute to several deleterious effects in the maple sugaring process and must be periodically removed by washing the evaporator pans. Small quantities of these impurities can degrade the quality of the flavor and color of the syrup. If left to build up on the pans, they can act as an insulator degrading thermal conduction between the sap and furnace decreasing the efficiency of evaporation. Thicker layers cause the stainless steel pan to over heat. This generates large stresses within the pan leading to distortion or cracking of the pan.
The front, finishing pans are usually small and easily detached from the furnace. They can be switched with a set of clean pans some times as often as every 4-6 hours of boiling time. The unclean finishing pans are cleaned when off of the evaporator by hand or with a portable washer. The larger rear flue pan, however, is typically 6×10 feet and not easily removed from the furnace. The rear flue pan must be washed in place with limited accessibility due to the steam hood above it. Washing occurs manually, is time consuming and hindered by the multitude of flues located in the bottom of the pan. With the added use of the reverse osmosis process, impurity concentrations are increased and sediments build more quickly in the rear flue pan requiring it to be cleaned more frequently.
In general, the prior art provides for no automated method or apparatus for the cleaning of evaporator pans while the pans are mounted on a maple sugar evaporator.